I, too, am dangerous with my shotgun and for a similar reason. Therefore, my self defense plan is thus: at the first sound, I grab the shot gun next to the bed and go to the top of the stairs. I then sit on the top step, resting said shotgun on knees. I then cock the gun and announce loudly, "That sound was my shotgun, and this staircase has just turned into a shooting gallery. Take one step on the stairs and I fire. I don't have to be accurate, At this range I'm gonna hit anything on the stairs." I figure that oughta do it.
Now, please. Let's not debate the merits, stupidity, impossibility, plausibility or other facets of this plan. It's MY plan and I'm sticking to it. Of course, I also live in a place that has almost no crime, so I'm not overly concerned, either.